This invention generally relates to a concept of providing an apparatus and method for determining true north without the use of a magnetic compass as well as a method for laying of azimuth lines from true north.
Various compass devices are known. Most common compasses utilize the principles of magnetism to locate north. These compasses, however, are greatly affected by naturally occurring magnetic perturbances which can lead to great inaccuracies. To avoid this problem, solar compasses have been proposed.
One such solar compass is described in U.S. Pat. No. 4,899,451, entitled "Solar Compass and Time Indicator Device", issued to Dandurand on Feb. 13, 1990. Dandurand's device, while providing a way to locate true north, lacked any means to correct for the location of the user (in terms of latitude). Additionally, Dandurand's device lacks the means to correct for the declination of the sun, which can vary significantly depending on the time of the year. Failure to correct for the location of the user and the declination of the sun introduces significant errors in finding true north. Aside from the errors in the location of true north, Dandurand's device also lacks the capability to sight off azimuth lines from true north.
Other solar compass have addressed some, but not all of these concerns. U.S. Pat. No. 4,028,813, entitled "Sun Compass" and issued to Eldridge on Oct. 22, 1975, corrects for the declination of the sun and the location of the user, but is very complex in composition and difficult to use.
It is clear from the foregoing that there is a need for an accurate, economical, easy to use solar compass and that the current state of the art is unable to meet this need.